HIF1A and neoplasm: To confirm that this reduction in tumour growth is specifically due to a lack of HIF-1α stabilization by NQO1, rather than through other NQO1 mediated effects, we studied the growth rate of control (RKO/pshCont1/pshCont2), NQO1 overexpressing (RKO/pNQO1/pshCont2), and NQO1 overexpressing but HIF-1α knockdown (RKO/pNQO1/pshHIF-1α) xenograft tumours.